Western blotting of platelet receptors confirmed a GPVI deficiency. SDS-soluble extracts of platelets from the patient (p) and a control donor (c) were separated by SDS-PAGE without disulfide reduction and transferred to nitrocellulose membrane. The membranes were probed for GPIb (Bx-1), αIIb (SZ22), β3 (XIIF9), and GPVI using the MoAbs F5 (A,B), 3J24.2 (C), and 9E18.2 (D). Bound antibody was located using a chemiluminescence procedure. GPIb, αIIb, and β3 were assessed using 10 μg protein, while GPVI was analyzed using 10 μg (A) and 20 μg (B-D) protein.